import java.lang.management.LockInfo;

public class hebinglianbiao {
    /**
     * 输入两个递增排序的链表，合并这两个链表并使新链表中的节点仍然是递增排序的。
     * 示例1：
     * 输入：1->2->4, 1->3->4
     * 输出：1->1->2->3->4->4
     */
    public class ListNode {
        int val;
        ListNode next;

        ListNode(int x) {
            val = x;
        }
    }

        public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
            if (l1 == null) {
                return l2;
            }
            if (l2 == null) {
                return l1;
            }
            ListNode start = null;
            ListNode end = null;
            while (l1 != null && l2 != null) {
                ListNode cur = l1.val < l2.val ? l1 : l2;
                if (cur == l1) {
                    l1 = l1.next;
                }else {
                    l2 = l2.next;
                }
                if (start == null) {
                    start = cur;
                    end = cur;
                }else {
                    end.next = cur;
                    end = cur;
                }
            }
            if (l1 == null) {
                end.next = l2;
            }else {
                end.next = l1;
            }
            return start;

    }
}
